Flip chip technology (also known as controlled collapse chip connection (C4)) is a method for interconnecting semiconductor devices to external circuitry with solder bumps that have been deposited onto chip pads. The solder bumps are deposited on the chip pads via an interconnect structure, during the final wafer processing step. In order to mount the chip to external circuitry (e.g., a circuit board or wafer), it is flipped over so that its top side faces down, and aligned so that its pads align with matching pads on the external circuitry. After such alignment is accomplished, the solder is flowed to complete the interconnect. This is in contrast to wire bonding, in which the chip is mounted upright and wires are used to interconnect the chip pads to external circuitry.
In flip chip interconnect technologies, the interconnect is typically formed in discrete steps from the global wiring structures. That is, the interconnect is formed in one set of processing steps; whereas, the global wiring structures such as, wires, inductors, etc., are formed in a different set of processing steps. This, in turn, requires additional masks. This, of course, increases manufacturing costs. Also, a reduction of critical device dimensions reduces required chip area which creates need for interconnect pitch reduction. This drives higher power requirements per area. Also, lower cost solder systems can be limited in power density by electromigration limits, and to compensate for this effect by using other materials can increase manufacturing costs.
Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove.